A growth of the gastrointestinal tract of weaned pigs as affected by crude fibre content in the diet was investigated on 16 piglets. Pigs of 10 kg body weight (BW) were offered a basal diet (group C and C₁) or diets formed by mixing a basal diet with 10 (diet GM₁₀) or 20% (diet GM₂₀) of grass meal (group F₁ and F₂, respectively). When pigs reached 25 kg BW animals of the groups F₁ and F ₂ were offered a basal diet, whereas those of the group C₁ were offered diet GM₂₀, following 14 days. Afterwards, animals were slaughtered; mass of the stomach, small and large intestines was recorded. The pigs of the group F₂ consumed by 8.8% more feed compared with the C and C ₁ pigs (1061 vs on average 979 g/day). However, the C and C₁ pigs grew faster (on average 535 g/day; P<0.01) than F₁ (462 g/day), and F₂ (443 g/day). A mass of the stomach of the both F₁ and F ₂ pigs was insignificantly heavier (by 6.7 and 20.6%, respectively) as compared with the C pigs. Mass of the large intestines of the F₁ and F₂ pigs was also heavier (by 4.6 and 4.2%, respectively) but small intestine of these pigs was insignificantly lighter (6.7 and 12.3%, respectively). Length of the small intestines of the F ₁ and F₂ pigs was lower (P<0.01; 32.3 and 30.1%, respectively), whereas length of their large intestine was unchanged. Correlation coefficients between previous fibre intake and mass of the stomach amounted 0.78 (P<0.009). However, a negative correlation between previous fibre intake and length of the small intestines (r= -0.68; P<0.06), as well as its weight (r= -0.45; P<0.07) were detected.